In 2023, Tigist Assefa of Ethiopia set a new record with a time of 2 hours, 11 minutes, and 53 seconds. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Assefa. What makes elite distance runners so good? Are their muscles somehow different from those of less successful athletes and non-athletes? Imagine that Tigist Assefa is racing against a bird and a fish, each with the same mass as Assefa. Which organism would have the highest cost of locomotion during the race?

Verified step by step guidance

1. Understand the concept of 'cost of locomotion', which refers to the amount of energy an organism expends to move a given distance. This cost is influenced by factors such as body structure, muscle composition, and the medium (air, water, land) through which the organism moves.
2. Consider the differences in muscle structure and function among the three competitors: a human (Tigist Assefa), a bird, and a fish. Humans have muscles optimized for endurance and long-distance running on land, birds have muscles adapted for flight which require quick bursts of energy, and fish have muscles suited for swimming with different resistance and buoyancy factors.
3. Analyze the medium of movement for each organism. Humans run on land where gravity plays a significant role, birds fly in the air which offers less resistance than water but requires energy to stay aloft, and fish swim in water where buoyancy reduces the impact of gravity but movement is met with more resistance.
4. Compare the efficiency of muscle use in each medium. Running on land generally requires more energy per unit of distance than swimming, due to the lack of buoyancy and continuous impact with the ground. Flying, while efficient over long distances, requires a lot of energy for takeoff and maintaining altitude.
5. Conclude which organism would likely have the highest cost of locomotion by considering the combined effects of muscle structure, function, and the medium of movement. Typically, organisms moving through air or on land tend to expend more energy compared to those moving in water, due to factors like gravity and resistance.

Key Concepts

Muscle Fiber Types

Muscle fibers are categorized into two main types: slow-twitch (Type I) and fast-twitch (Type II). Slow-twitch fibers are more efficient for endurance activities, as they use oxygen to generate energy and are resistant to fatigue. In contrast, fast-twitch fibers are geared towards short bursts of power and speed but fatigue quickly. Elite distance runners typically have a higher proportion of slow-twitch fibers, which enhances their endurance and performance in long races.

Cost of Locomotion

The cost of locomotion refers to the energy expenditure required for an organism to move over a certain distance. It is influenced by factors such as body mass, muscle efficiency, and the mode of locomotion (running, flying, swimming). In comparing Tigist Assefa with a bird and a fish, the cost of locomotion can vary significantly due to differences in biomechanics and energy use, with each organism adapting its movement to optimize efficiency in its environment.

Biomechanics of Locomotion

Biomechanics involves the study of the mechanical laws relating to the movement or structure of living organisms. In the context of locomotion, it examines how muscles, tendons, and skeletal structures work together to produce movement. For instance, the running mechanics of a human differ from the flight mechanics of a bird or the swimming mechanics of a fish, affecting their speed, efficiency, and ultimately the cost of locomotion during a race.